The mechanisms responsible for mixing the ocean are complex and variable in both space and time. Although they occur on scales smaller than can be resolved on the best oceanographic numerical models, their contribution is significant to a model's capabilities. Mixing in the upper ocean (typically the upper hundred meters or less) is due largely to surface (atmospheric) forcing. The various effects of surface heating/cooling, winds and surface waves contribute distinct (though not completely understood) signatures to turbulence observed beneath the ocean's surface. It is in the ocean's upper layers that atmosphere and ocean are most strongly coupled. Heat, gases and momentum are transported across the air-sea interface by small-scale processes. Quantifying the net transfer rates is an especially difficult but important task for experimenters and modellers.
In the deep ocean, turbulence is weaker and the physics of mixing less direct. Numerous measurements suggest that turbulence in the deep ocean is too weak to mix the fluid to its present state. It has been suggested that the fluid is mixed at the ocean's boundaries and transported to mid-gyre by poorly-understood processes. The search for the deep mixing is now one of the most important research areas in physical oceanography.
COAS scientists study various aspects of ocean mixing. These studies include design of new experiments and sensing techniques for observing turbulence and other small-scale physical processes in the ocean and modeling of some of the processes involved. Strong collaborations between experimenters and modelers are an integral part of the work at COAS.
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